There are layer-connecting fabrics made of cotton or wool in the civil textile, which are also known as warp pile wool fabrics. The typical sorts are plain velvet fabric and plush fabric etc. Their common features are the use of double layer-connecting weave and that poil warps with only differences in length and density are uniformly sandwiched between the upper and lower layer weave by certain weaving design. For example, the upper layer weave of plain velvet weave (see FIG. 1) is formed by crossing warp yarns 1, 2 in pair with a row of weft yarns 3; the lower layer weave is formed by crossing warp yarns 4, 5 in pair with a row of weft yarns 6; and the double layer-connecting structure is formed by crossing poil warps 7, 8 with respective weft yarns of the upper and lower layers. The plain velvet fabric is finally made after the poil-cutting process. Poil warps of such fabric are connected with the upper and lower layer weaves by a “forward” (namely in the same direction as the weft-inserting direction of the fabric) manner of crossing for the reason that poil warps are respectively crossed with different weft yarns of different layers. The manner of crossing has problems that the fastness of crossing is low, the cloth fell oscillates greatly up and down during the weaving process and the pile height is limited. The length of poil warps of the plain velvet fabric is about 2 mm, and the length of poil warps of the plush fabric is about between 10 and 18 mm which needs special weaving manner. The products made of the plush fabrics are mostly used in the garment industry for achieving a certain costume effect. The layer-connecting fabrics are also widely used in architectural engineering, such as greatly-used geofabric and layer-connecting fabric used in the banks of reservoir.
In addition, the Chinese patent (00135845.6) introduces a hollow layer-connecting composite material, wherein the upper and lower layers of the fabric are connected “forwardly” by a poil warp; the pile height is 20-600 mm; the spatial height of the fabric is comparatively huge; the fabric is used to produce sound-proof materials and filling materials. However, it has the defects that the connecting manner of poil warps is simple, and spatial structure lacks variation. The lower strength of the framework of the composite material of the fabric affects its use as a structure material. European patent (DLE19609492), (93119483.1) and American patent (U.S. Pat. No. 5,175,034) introduce several kinds of layer-connecting fabrics. But in all the fabrics mentioned by these patents, the poil warps are crossed “forwardly” respectively with different weft yarns on each layer. The poil warps using such manner of crossing are easy to slidably move such that the fastness of poil warps is influenced. Therefore, the framework feature of the layer-connecting fabric made by the “forward” manner of crossing is not distinct, nor is the vertical support function of poil warps between two layers. These render the anti-pressure strength of the composite material decreasing and the mechanical properties fluctuating greatly. At present, the “forward” crossing structure of poil warps is adopted in weaving all kinds of layer-connecting fabrics developed home and abroad.